What is influenza?
Influenza is a contagious disease caused by a virus that infects many parts of the body, including the lungs. Up to 20% of people may catch influenza each year1.
When someone who has influenza sneezes, coughs or even talks the influenza virus is expelled into the air and may be inhaled by anyone close by. In adults, symptoms can include fever, cough, sore throat, fatigue, muscle aches, headaches, runny nose and watery eyes. Although the fever and body aches usually last for 3-5 days, a cough and fatigue may persist for 2 weeks or more.
In healthy adults, influenza is regarded as a moderately severe illness. For people who are not healthy to begin with, influenza can be very severe or even fatal with the additional complications usually caused by bacterial infection.
The period between infection and onset of symptoms is 1-4 days. A person may be contagious with the influenza.
1. Nichol KL. Clinical effectiveness and cost-effectiveness of influenza vaccination among health working adults. Vaccine 1999, 17:567-73.